Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add woliveiras/geremmyas --skill gameplay-programming-2dgit clone --depth 1 https://github.com/woliveiras/geremmyasWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/woliveiras/geremmyas/gameplay-programming-2d)<a href="https://agentmods.dev/skills/woliveiras/geremmyas/gameplay-programming-2d"><img src="https://agentmods.dev/badge/skills/woliveiras/geremmyas/gameplay-programming-2d/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/woliveiras/geremmyas/gameplay-programming-2d"><img src="https://agentmods.dev/badge/skills/woliveiras/geremmyas/gameplay-programming-2d.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00059 | $0.00533 |
| Opus 5 | $0.00030 | $0.00267 |
| Sonnet 5 | $0.00012 | $0.00107 |
| Haiku 4.5 | $0.00006 | $0.00053 |
Grade A, and why
gameplay-programming-2d scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 49 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Gameplay Programming 2D
Build gameplay as explicit, testable simulation rules with engine code at the boundary.
Start from project evidence
- Read the nearest repository instructions and existing gameplay code.
- Detect the engine, exact installed version, language, physics backend, target platforms, and test setup.
- Identify the current ownership of input, simulation, presentation, collision, and persistence.
- Preserve established conventions unless they cause the reported problem.
- Define the requested behavior with measurable states, transitions, timing, and failure cases.
Load only relevant references
- Read shared-foundations.md for architecture, time, state, collision, combat, and contracts.
- For Phaser, also read phaser.md.
- For Godot, also read godot.md.
- Use
$game-testing-2dfor a test strategy,$game-feel-2dfor responsiveness and feedback, and$game-art-2dfor visual assets.
Implement a vertical behavior
- Express gameplay inputs as intentions, not device keys.
- Keep authoritative state independent of sprites, animation frames, and visible bounds.
- Choose update ownership and time domain explicitly.
- Implement one complete behavior from input or stimulus through state change to presentation.
- Keep physics bodies, hitboxes, hurtboxes, sockets, and navigation as gameplay data.
- Make one-shot events idempotent and define interruption rules.
- Clean up subscriptions, timers, tweens, nodes, and pooled objects at lifecycle boundaries.
Verify
- Test state transitions, frame-rate independence, collision boundaries, interruptions, and repeated entry.
- Exercise low and high frame rates plus pause, resume, scene reload, and object destruction.
- Inspect the behavior in a running build at the target resolution and input devices.
- Report automated evidence separately from subjective play-feel acceptance.
Guardrails
- Do not derive damage or collision from opaque pixels.
- Do not let animations silently own gameplay truth.
- Do not mix milliseconds and seconds or render and physics clocks.
- Do not introduce a global manager when local scene ownership is sufficient.
- Do not rewrite the architecture before proving the existing boundary cannot support the behavior.
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 10d ago First seen · 49 lines · 59 tokens per session scan A 71d424d54f5b
gameplay-programming-2d is a skill published in the GitHub repository woliveiras/geremmyas (10 stars, last pushed 1mo ago), licensed MIT. It adds 59 tokens to every session and 533 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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